<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h1>这是index.html页面的内容</h1>
    <button onclick="getHttp()">点击发送一个get请求</button>

   <script>
    function getHttp(){
        var xhr = new XMLHttpRequest();
        xhr.onreadystatechange = function(){
            if(xhr.readyState ===4){
                console.log(xhr.responseText);
            }
        }

        xhr.open('get','http://localhost:3000/getOne');
        xhr.send();
    }
   </script>

</body>
</html>